In the extensively used snap-fitted low voltage electrical appliances such as a reversible contactor group composed of two contactors, for the sake of normal and safe operation thereof, a mechanical interlocking function is required between the two contactors, i.e., when any one of the two contactors is in an energized state, the other contactor cannot be energized, i.e., it is locked in a disconnected state.
In a multi-loop circuit system, an electrical appliance group made of over two snap-fitted electrical appliances is needed. To ensure normal and safe operation of the appliance group, a mechanical interlocking function is required between the appliances, that is to say, at the same time only one of the appliances is allowed to be energized whereas the remaining adjacent two appliances are locked in a disconnected state.
Taking contactors as an example, currently the commonly used interlock type contactor group comprises two individual contactors and one interlock means. The prior-art interlock means has a relatively complicated structure with too many components and occupies too much space.
The Chinese utility model patent ZL200520026452.3 discloses a technology regarding a mechanical interlocking module of a reversible AC contactor. The mechanical interlocking module comprises a housing, a ram head-shaped interlocking member, two push rods and two contact holders. Each of the contact holders is provided with a screw rod fixedly coupled to the push rod and a bridge-like contact. The two push rods respectively abut against left and right ram horns of the ram head-shaped interlocking member. An internally threaded insert mating with the screw rod is fixedly connected to each of the contact holders. Such mechanical interlocking module in the prior art has a working principle as follows: the two contact holders are allowed by the internally threaded inserts on the two contact holders to bring the screw rod into motion, further urge the push rods which in turn push the left and right ram horns of the ramhead-shaped interlocking member into a locked position, thereby accomplishing the interlocking function.
The prior art appliance requires a large number of components and therefore leads to issues such as difficult manufacturing, a high processing cost and a large size. Furthermore, each of the contactors in the contactor group cannot be used as an independent contactor, or vice versa, independent contactors cannot be combined into a contactor group, i.e., free combination and mutual interlocking of two or more contactors cannot be fulfilled. All the above give too many limitations to the application of that technology.